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				<div class="sectiontitle">ISANTA Clipped-Head Nail Study</div>

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					Researchers who tested clipped-head and casing nails at Virginia Polytechnic University found
					that clipped-head nails perform just as well as full round-head nails. They tested plywood
					specimens nailed to lumber and loaded in shear, which reflects how nails connecting shear
					panels to wood framing would be loaded.<br />
					<br />
					The following is from the Conclusions section of their study:<br />
					<br />
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						"...there is not a satistically significant difference between the clipped-head and full-head
						nails, regardless of the orientation of the clipped edge with respect to the load or plywood
						face-grain direction."
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					<br />
					It should be noted that the results of these tests go against what common engineering judgment
					would predict. Without further knowledge of the testing procedures and results, we recommend
					using full round-head nails.<br />
					<br />
					You may e-mail ISANTA at <a href="mailto:Isanta@Ameritech.net">Isanta@Ameritech.net</a> or telephone
					them at (708) 482-8138 and request a copy of the study, which is titled "Cyclic Tests of Casing and
					Clipped Head Nail Connections."
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				<div class="sectiontitle">"Green" Framing Lumber used in Shear Walls</div>

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					Section 3.1.3 of the Shear Wall Construction Guide mentions that the strength of nails driven
					into green lumber (lumber with a moisture content of 19% or more--usually "S-Grn" appears in the
					grade-stamp) will have less strength than nails driven into dry lumber. The APA tested eight shear
					walls, six framed with green lumber and two with seasoned lumber. They report that the ultimate
					strength of the walls was not significantly different. However, they say that the stiffness of the
					shear walls built with green lumber was less than the walls built with dry lumber. Remember that
					stiffness is very important in preventing damage to building finishes.<br />
					<br />
					For more information, see APA's Technical Bulletin <a href="http://www.apawood.org/pdfs/managed/TT-075.pdf">
					TT-075</a> and APA Report <a href="http://www.apawood.org/pdfs/tsd/T-Reports/T2002-53.pdf">T21002-53</a>
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				<div class="sectiontitle">Shear Walls with Sloping Top Chords</div>

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					Appendix B of Wood-Framed Shear Wall Construction--an Illustrated Guide discusses the correct way
					to analyze an isolated shear wall that is taller at one end than the other. Since sloping shear
					walls are rarely isolated, other parts of the structural system will usually help keep the shear
					wall from failing if it is not designed properly.<br />
					<br />
					One structural engineer and researcher in the field of earthquake design had this to say:
					"What you are showing is one small part of a folded plate diaphragm system that I do not think any
					of us really understand at this point.... Because roof diaphragms are not a significant source of
					earthquake damage, they are not currently a high priority for testing, so we remain trying to
					develop mehcanics-based models without really knowing."<br />
					<br />
					Engineers do analyze wood-framed systems by making many simplifications. But the shear wall will
					suffer more damage than the roof diaphragm because the forces in the roof diaphragm get
					"concentrated" at shear walls.<br />
					<br />
					Until someone comes forward with a more accurate analytical model or some test results that show
					how sloping shear walls really behave, engineers should analyze sloping shear walls in way that
					best reflects reality. This is the method presented in Appendix B of Wood-Framed Shear Wall
					Construction--an Illustrated Guide<br />
					<br />
					Engineers and other brave technical types can find even further discussion in the "Appendix to the
					Appendix". This is included at the end of <a href="http://www.shearwalls.com/resources/appendix-b.pdf">APPENDIX B</a>.
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				<div class="sectiontitle">Have News?</div>

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					<b>Submit your own</b> news item or discussion topic - send e-mail to: faq "at" shearwalls.com
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